A group of NIH funded scientists at the University of Florida, Gainesville campus, are requesting funds to purchase a Nikon A1R two-photon microscope system capable of imaging dynamic processes in thick samples. There currently is no two-photon instrument at any of the shared core facilities on the University of Florida Gainesville campus. This application describes the immediate needs of our NIH funded research faculty for an instrument capable of both two-photon imaging, providing the Z-depth resolution needed to capture protein movement in living tissue, as well as high-speed resonance scanning with an integrated perfect focus system to capture fast cellular events. The existing confocal and wide-field microscopes at the UF imaging core facility are maximally used, or are outdated and cannot be upgraded to accomplish the imaging needs of the major and minor users of this application. As with the current instruments, the proposed two- photon system will be housed and managed in the shared Cell and Tissue Analysis Core Facility (CTAC). All major and minor users will have access to the instrument and training will be provided through the established CTAC infrastructure. The usage charges and institutional funding have supported the service contract, supplies, and the CTAC personnel; therefore, we foresee no difficulty in this arrangement continuing for the Nikon A1R two-photon system. In addition, the CTAC will train the users of the two-photon instrument, as required by their research projects. The shared CTAC facility has an extensive track record of education, training and productivity with over 190 lab groups at the University of Florida. During the past seven years, the imaging core has introduced shared access to confocal microscopy, live cell imaging, and whole animal imaging. The UF research community now extensively uses these advanced microscopy techniques. For imaging of thick intact tissue, two-photon excitation is far superior to other approaches and permits high-resolution imaging at a level 5 to 10 fold deeper than with confocal microscopy. The proposed two-photon instrument will be the only generally available two-photon imaging system at the University of Florida. The availability of this technology is crucial for the mission of the University of Florida with the overall goal of finding treatments fo human disease and to train the next generation of outstanding investigators in biomedical sciences.